Comment Power to weight ratio (Score 4, Informative) 167
to put 8 kW/kg into perspective, all commercial brushless dc motors are at 4 kW/kg and it is a limitation of the materials used.
Commercial internal combustion engines range from 1 kW/kg to *maybe* 3 kW/kg if it is turbocharged to the point of sacrificing engine longevity and formula 1 engines are at around 5 kW/kg
although i suspect they saved weight by using the vehicle frame as (part of?) the stator, a perk of making a motor for a very specific purpose.